Calf Muscle Density Research Articles

PHYSICAL ACTIVITY, SEDENTARY BEHAVIORS AND MYOSTEATOSIS IN AFRICAN CARIBBEANS

Abstract Skeletal muscle fat infiltration (myosteatosis) leads to poorer muscle quality and function with aging, and is emerging as a predictor of skeletal muscle strength, mobility, and metabolic disorders. Few studies investigated the association of physical activity (PA) and sedentary behavior (SB) with myosteatosis, especially in African Caribbeans, a vastly under-studied, rapidly growing population. We examined the associations of objectively measured PA and SB (Bodymedia SenseWear Armbands) worn over 7 days with calf muscle density (mg/cm3), a marker of intra-muscular fat (Stratec XCT-2000), in older adult African Caribbean men (N=355, mean age 62 years) and women (N=682, mean age 59 years) of the Tobago Health Study. Compared to men, women were younger with higher BMI, more SB, less light (LPA) and moderate to vigorous PA (MVPA), and lower muscle density (p< 0.05, age-adjusted). Meeting MVPA guidelines (150 min MVPA/week) was associated with greater muscle density in obese men and women (p=0.03, p=0.09 respectively, age-adjusted). Adjusting for age, BMI, smoking, diabetes, hypertension, and lipid-lowering treatment, we assessed sex stratified partial spearman correlations between PA and SB and muscle density. MVPA was more strongly correlated with greater muscle density in men (r=0.15, p=0.01) than in women (r=0.07, p=0.09), while SB was associated with lower muscle density in women (r=-0.08, p=.044), but not significantly in men (r=-0.10, p=0.12). Our novel findings indicate that the association between PA and SB with myosteatosis may differ by sex. These findings may have important implications for sex specific activity guidelines related to skeletal muscle health in African Caribbeans.

Carnosine supplementation improves glucose control in adults with pre-diabetes and type 2 diabetes: A randomised controlled trial

Background and aimsType 2 diabetes (T2DM) is a major cause of morbidity and mortality globally. Carnosine, a naturally occurring dipeptide, has anti-inflammatory, antioxidant, and anti-glycating effects, with preliminary evidence suggesting it may improve important chronic disease risk factors in adults with cardiometabolic conditions. Methods and resultsIn this randomised controlled trial, 43 adults (30%F) living with prediabetes or T2DM consumed carnosine (2 g) or a matching placebo daily for 14 weeks to evaluate its effect on glucose metabolism assessed via a 2-h 75 g oral glucose tolerance test. Secondary outcomes included body composition analysis by dual energy x-ray absorptiometry (DEXA), calf muscle density by pQCT, and anthropometry. Carnosine supplementation decreased blood glucose at 90 min (−1.31 mmol/L; p = 0.02) and 120 min (−1.60 mmol/L, p = 0.02) and total glucose area under the curve (−3.30 mmol/L; p = 0.04) following an oral glucose tolerance test. There were no additional changes in secondary outcomes. The carnosine group results remained significant before and after adjustment for age, sex, and change in weight (all>0.05), and in further sensitivity analyses accounting for missing data. There were no significant changes in insulin levels. ConclusionThis study provides preliminary support for larger trials evaluating carnosine as a potential treatment for prediabetes and the initial stages of T2DM. Likely mechanisms may include changes to hepatic glucose output explaining the observed reduction in blood glucose without changes in insulin secretion following carnosine supplementation.

Greater pQCT Calf Muscle Density Is Associated with Lower Fracture Risk, Independent of FRAX, Falls and BMD: A Meta-Analysis in the Osteoporotic Fractures in Men (MrOS) Study.

We investigated the predictive performance of peripheral quantitative computed tomography (pQCT) measures of both calf muscle density (an established surrogate for muscle adiposity, with higher values indicating lower muscle adiposity and higher muscle quality) and size (cross-sectional area [CSA]) for incident fracture. pQCT (Stratec XCT2000/3000) measurements at the tibia were undertaken in Osteoporotic Fractures in Men (MrOS) United States (US), Hong Kong (HK), and Swedish (SW) cohorts. Analyses were by cohort and synthesized by meta-analysis. The predictive value for incident fracture outcomes, illustrated here for hip fracture (HF), using an extension of Poisson regression adjusted for age and follow-up time, was expressed as hazard ratio (HR) per standard deviation (SD) increase in exposure (HR/SD). Further analyses adjusted for femoral neck (fn) bone mineral density (BMD) T-score, Fracture Risk Assessment Tool (FRAX) 10-year fracture probability (major osteoporotic fracture) and prior falls. We studied 991 (US), 1662 (HK), and 1521 (SW) men, mean ± SD age 77.0 ± 5.1, 73.9 ± 4.9, 80 ± 3.4 years, followed for a mean ± SD 7.8 ± 2.2, 8.1 ± 2.3, 5.3 ± 2.0 years, with 31, 47, and 78 incident HFs, respectively. Both greater muscle CSA and greater muscle density were associated with a lower risk of incident HF [HR/SD: 0.84; 95% confidence interval [CI], 0.72-1.0 and 0.78; 95% CI, 0.66-0.91, respectively]. The pattern of associations was not materially changed by adjustment for prior falls or FRAX probability. In contrast, after inclusion of fn BMD T-score, the association for muscle CSA was no longer apparent (1.04; 95% CI, 0.88-1.24), whereas that for muscle density was not materially changed (0.69; 95% CI, 0.59-0.82). Findings were similar for osteoporotic fractures. pQCT measures of greater calf muscle density and CSA were both associated with lower incidence of fractures in older men, but only muscle density remained an independent risk factor for fracture after accounting for fn BMD. These findings demonstrate a complex interplay between measures of bone, muscle size, and quality, in determining fracture risk. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Determinants of muscle density and clinical outcomes: Findings from the Hertfordshire Cohort Study.

The age-related loss of skeletal muscle mass and strength is associated with adverse health outcomes. However, to date, peripheral quantitative computed tomography (pQCT)-derived muscle density has been little studied. We used a well characterised cohort of older adults to identify lifestyle and anthropometric determinants of pQCT-derived muscle density measured 11years later, and to report relationships between pQCT-derived muscle density with history of falls and prevalent fractures. A lifestyle questionnaire was administered to 197 men and 178 women, aged 59-70 at baseline. After a median of 11.5 (IQR 10.9, 12.3) years, pQCT (Stratec XCT2000) of the radius and tibia was performed to measure forearm muscle density (FMD) and calf muscle density (CMD). Presence of falls and fractures since the age of 45 were determined through participant recall; vertebral fractures were also ascertained through vertebral fracture assessment using iDXA. Total hip BMD (TH aBMD) was assessed using DXA. Baseline characteristics in relation to muscle density at follow-up were examined using linear regression; associations between muscle density and prior falls and fractures were investigated using logistic regression. All analyses were adjusted for sex and age. Mean (SD) age at muscle density measurement was 76.3 (2.6) years. Mean (SD) FMD was 79.9 (3.1) and 77.2 (3.2) among males and females, respectively; CMD was 80.7 (2.6) and 78.5 (2.6) among males and females, respectively. Significant sex-differences in muscle density were observed at each site (p<0.001). Female sex, lower weight, and lower body mass index were associated (p<0.05) with both lower FMD and CMD. Additional correlates of lower CMD included older age and shorter stature. Lifestyle measures were not associated with muscle density in this cohort. Lower FMD was related to increased risk of previous fracture (odds ratio (95% CI) per SD lower FMD: 1.42 (1.07, 1.89), p=0.015) but not after adjustment for TH aBMD (p>0.08). No significant relationships were seen between muscle density and falls. Female sex, older age, and lower BMI were associated with subsequent lower muscle density in older community-dwelling adults. Lower FMD was related to increased risk of previous fracture. Changes in muscle density over time might precede adverse outcomes such as falls and fractures and may be a long-term predictor of frailty. It could be also suggested that muscle density could be a more clinically meaningful surrogate of functional decline and disability than muscle size or mass, but more studies are needed to support this notion.

738 DETERMINANTS OF MUSCLE DENSITY IN OLDER PEOPLE: FINDINGS FROM THE HERTFORDSHIRE COHORT STUDY (HCS)

Abstract Introduction Lower calf muscle density (CMD) as assessed by peripheral quantitative computed tomography (pQCT) is associated with greater hip fracture risk, independent of FRAX, falls and bone mineral density. To date, muscle density has been little studied, and its determinants are unknown. In this study, we examine the lifestyle and anthropometric determinants of future muscle density (MD) in the HCS. Methods 197 men and 178 women, aged 59–70 years, were recruited. A lifestyle questionnaire collected information on physical activity, smoking, alcohol consumption and dietary patterns. Height and weight were measured. pQCT of the radius and tibia was performed a median of 11.5 (IQR 10.9, 12.3) years later. MD was measured at calf and forearm using standard methodology. Baseline characteristics in relation to MD at follow-up were examined separately using linear regression with sex, baseline age and follow-up time included as covariates in all models. Results Mean (SD) age at baseline was 64.7 (2.7) years; mean (SD) MD values (mg/cm3) were as follows: forearm [men 79.9 (3.1), women 77.2 (3.2)], calf [men 80.7 (2.6), women 78.5 (2.6)]. Baseline correlates (p &amp;lt; 0.05) of both lower forearm and CMD included female sex, lower weight, and lower BMI. SD difference in CMD for women compared to men, and per SD lower weight and BMI were − 0.84 [95%CI: −1.13, −0.54]), −0.37 [−0.46, −0.27] and − 0.31 [−0.40, −0.23] respectively. Additional correlates of lower CMD included older age and shorter stature. Relationships between MD and age were stronger at the calf (p &amp;lt; 0.001) than the forearm (p = 0.08). Lifestyle measures were not associated with MD. Conclusion Female sex, older age, and lower BMI were associated with lower MD in older community-dwelling adults, highlighting the need for sustained muscle conditioning in older individuals. Further studies in larger cohorts are required.

Water Extract of Lotus Leaf Alleviates Dexamethasone-Induced Muscle Atrophy via Regulating Protein Metabolism-Related Pathways in Mice.

Muscle atrophy is an abnormal condition characterized by loss of skeletal muscle mass and function and is primarily caused by injury, malnutrition, various diseases, and aging. Leaf of lotus (Nelumbo nucifera Gaertn), which has been used for medicinal purposes, contains various active ingredients, including polyphenols, and is reported to exert an antioxidant effect. In this study, we investigated the effect of water extract of lotus leaf (LL) on muscle atrophy and the underlying molecular mechanisms of action. Amounts of 100, 200, or 300 mg/kg/day LL were administered to dexamethasone (DEX)-induced muscle atrophy mice for 4 weeks. Micro-computed tomography (CT) analysis revealed that the intake of LL significantly increased calf muscle volume, surface area, and density in DEX-induced muscle atrophy mice. Administration of LL recovered moving distance, grip strength, ATP production, and body weight, which were decreased by DEX. In addition, muscle damage caused by DEX was also improved by LL. LL reduced the protein catabolic pathway by suppressing gene expression of muscle atrophy F-Box (MAFbx; atrogin-1), muscle RING finger 1 (MuRF1), and forkhead box O (FoxO)3a, as well as phosphorylation of AMP-activated kinase (AMPK). The AKT-mammalian target of the rapamycin (mTOR) signal pathway, which is important for muscle protein synthesis, was increased in LL-administered groups. The HPLC analysis and pharmacological test revealed that quercetin 3-O-beta-glucuronide (Q3G) is a major active component in LL. Thus, Q3G decreased the gene expression of atrogin-1 and MuRF1 and phosphorylation of AMPK. This compound also increased phosphorylation levels of mTOR and its upstream enzyme AKT in DEX-treated C2C12 cells. We identified that LL improves muscle wasting through regulation of muscle protein metabolism in DEX-induced muscle atrophy mice. Q3G is predicted to be one of the major active phenolic components in LL. Therefore, we propose LL as a supplement or therapeutic agent to prevent or treat muscle wasting, such as sarcopenia.

Skeletal Muscle Pathology in Peripheral Artery Disease: A Brief Review.

This brief review summarizes current evidence regarding lower extremity peripheral artery disease (PAD) and lower extremity skeletal muscle pathology. Lower extremity ischemia is associated with reduced calf skeletal muscle area and increased calf muscle fat infiltration and fibrosis on computed tomography or magnetic resonance imaging. Even within the same individual, the leg with more severe ischemia has more adverse calf muscle characteristics than the leg with less severe ischemia. More adverse computed tomography-measured calf muscle characteristics, such as reduced calf muscle density, are associated with higher rates of mobility loss in people with PAD. Calf muscle in people with PAD may also have reduced mitochondrial activity compared with those without PAD, although evidence is inconsistent. Muscle biopsy document increased oxidative stress in PAD. Reduced calf muscle perfusion, impaired mitochondrial activity, and smaller myofibers are associated with greater walking impairment in PAD. Preliminary evidence suggests that calf muscle pathology in PAD may be reversible. In a small uncontrolled trial, revascularization improved both the ankle-brachial index and mitochondrial activity, measured by calf muscle phosphocreatine recovery time. A pilot clinical trial showed that cocoa flavanols increased measures of myofiber health, mitochondrial activity, and capillary density while simultaneously improving 6-minute walk distance in PAD. Calf muscle pathological changes are associated with impaired walking performance in people with PAD, and interventions that both increase calf perfusion and improve calf muscle health are promising therapies to improve walking performance in PAD.

Abstract P462: Myosteatosis: Differences in Association With Type 2 Diabetes by Anatomical Location

Background: CT-derived muscle density (MD) reflects the degree of adiposity in muscle (i.e., myosteatosis) with lower MD indicating greater adiposity. Previous research indicates lower MD is associated with increased risk of type 2 diabetes (T2D). However, few studies have compared the association of simultaneously measured MD by anatomic location. The relationship between myosteatosis and cardiometabolic health may differ by body site and influence which location(s) is most useful for risk assessment. We investigated potential differential relationships between T2D and MD of the locomotor muscles of the abdomen (psoas), thigh, and calf among 539 African Caribbean men from Tobago. Methods: Men were aged 50-91 years (mean 64.4 years, mean BMI 27.5 kg/m 2 ). Calf MD was measured at 66% of calf length using peripheral quantitative CT; calf MD was defined as the ratio of muscle mass to cross-sectional muscle area. Psoas MD was measured in the abdomen (between L3/L4) and thigh MD was measured in the mid-thigh using CT; for these, MD was defined as the average muscle attenuation across each site. MDs were converted to per-SD units for comparability. T2D was defined as a fasting serum glucose level of ≥126 mg/dL or currently taking antidiabetic medication. Results: Psoas and thigh MDs were more highly correlated (r = 0.70) than psoas and calf (r = 0.33) or thigh and calf (r = 0.53) MDs, and calf MD was moderately correlated with BMI (r = -0.38) compared to lower BMI correlations for thigh (r = -0.18) or psoas (r = -0.16) MDs (all significant p &lt; 0.05). After age and lifestyle factor adjustment (Table), a 1-SD lower MD of the thigh or calf was significantly associated with higher odds of T2D. Additional adjustment for BMI completely attenuated the association with T2D for thigh MD, but not calf MD. Conclusion: In our study of African Ancestry men, only calf MD was associated with higher odds of T2D independent of BMI and other muscle groups. Longitudinal studies are needed to better characterize specific muscle myosteatosis and metabolic abnormalities.

Postural control is associated with muscle power in post-menopausal women with low bone mass.

Post-menopausal women with low bone mass are at higher risk of bone fractures subsequent to falls. Understanding the correlates of postural control in this collective informs intervention design for falls prevention. We examined postural control in single-leg stance on stable and unstable surfaces in 63 community-dwelling post-menopausal women with osteopenia or osteoporosis but without diagnosed neuromuscular, vestibular or arthritic diseases. Postural measures were compared to countermovement jump performance (height, force and power), leg-press strength (10 repetition maximum), calf muscle area and density (via peripheral quantitative computed tomography), body mass, height and age. On step-wise regression, peak countermovement jump power and jump height (p≤ 0.014), but not jump force, leg-press strength or calf muscle size, were related to postural control in single-leg stance on, respectively, an unstable surface (eyes open) and standing on a stable surface (eyes open). None of the parameters measured were significantly related to the postural control parameters in single-leg stance on a stable surface with eyes closed. With testing on the stable surface, body mass was associated with slow mean centre of pressure movement speed (p≤ 0.030). Our findings show that, in post-menopausal women with low bone mass, neuromuscular power is a more important determinant of postural control than muscle strength or size. Our findings provide evidence to support the integration of power or speed training into falls prevention and balance training programs in post-menopausal women with osteopenia and osteoporosis.

Increased density and periosteal expansion of the tibia in young adult men following short-term arduous training

PurposeFew human studies have reported early structural adaptations of bone to weight-bearing exercise, which provide a greater contribution to improved bone strength than increased density. This prospective study examined site- and regional-specific adaptations of the tibia during arduous training in a cohort of male military (infantry) recruits to better understand how bone responds in vivo to mechanical loading. MethodsTibial bone density and geometry were measured in 90 British Army male recruits (ages 21±3years, height: 1.78±0.06m, body mass: 73.9±9.8kg) in weeks 1 (Baseline) and 10 of initial military training. Scans were performed at the 4%, 14%, 38% and 66% sites, measured from the distal end plate, using pQCT (XCT2000L, Stratec Pforzheim, Germany). Customised software (BAMPack, L-3 ATI) was used to examine whole bone cross-section and regional sectors. T-tests determined significant differences between time points (P<0.05). ResultsBone density of trabecular and cortical compartments increased significantly at all measured sites. Bone geometry (cortical area and thickness) and bone strength (i, MMi and BSI) at the diaphyseal sites (38 and 66%) were also significantly higher in week 10. Regional changes in density and geometry were largely observed in the anterior, medial–anterior and anterior–posterior sectors. Calf muscle density and area (66% site) increased significantly at week 10 (P<0.01). ConclusionsIn vivo mechanical loading improves bone strength of the human tibia by increased density and periosteal expansion, which varies by site and region of the bone. These changes may occur in response to the nature and distribution of forces originating from bending, torsional and shear stresses of military training. These improvements are observed early in training when the osteogenic stimulus is sufficient, which may be close to the fracture threshold in some individuals.

Adverse Fat Depots and Marrow Adiposity Are Associated With Skeletal Deficits and Insulin Resistance in Long-Term Survivors of Pediatric Hematopoietic Stem Cell Transplantation.

Allogeneic hematopoietic stem-cell transplantation (alloHSCT) survivors treated with total body irradiation (TBI) exhibit bone deficits and excess adiposity, potentially related to altered mesenchymal stem cell differentiation into osteoblasts or adipocytes. We examined associations among fat distribution, bone microarchitecture, and insulin resistance in alloHSCT survivors after TBI. This was a cross-sectional observational study of 25 alloHSCT survivors (aged 12 to 25 years) a median of 9.7 (4.3 to 19.3) years after alloHSCT compared to 25 age-, race-, and sex-matched healthy controls. Vertebral MR spectroscopic imaging and tibia micro-MRI were used to quantify marrow adipose tissue (MAT) and trabecular microarchitecture. Additional measures included DXA whole-body fat mass (WB-FM), leg lean mass (Leg-LM), trunk visceral adipose tissue (VAT), and CT calf muscle density. Insulin resistance in alloHSCT survivors was estimated by HOMA-IR. AlloHSCT survivors had lower Leg-LM (p < 0.001) and greater VAT (p < 0.01), MAT (p < 0.001), and fat infiltration of muscle (p = 0.04) independent of WB-FM, versus matched controls; BMI did not differ. Survivors had lower bone volume fraction and abnormal microarchitecture including greater erosion and more rod-like structure versus controls (all p = 0.04); 14 had vertebral deformities and two had compression fractures. Greater WB-FM, VAT, MAT, and muscle fat infiltration were associated with abnormal trabecular microarchitecture (p < 0.04 for all). AlloHSCT HOMA-IR was elevated, associated with younger age at transplantation (p < 0.01), and positively correlated with WB-FM and VAT (both p < 0.01). In conclusion, the markedly increased marrow adiposity, abnormal bone microarchitecture, and abnormal fat distribution highlight the risks of long-term treatment-related morbidity and mortality in alloHSCT recipients after TBI. Trabecular deterioration was associated with marrow and visceral adiposity. Furthermore, long-term survivors demonstrated sarcopenic obesity, insulin resistance, and vertebral deformities. Future studies are needed to identify strategies to prevent and treat metabolic and skeletal complications in this growing population of childhood alloHSCT survivors.

Muscle activity, cross-sectional area, and density following passive standing and whole body vibration: A case series

ObjectiveTo investigate the effects of intermittent passive standing (PS) and whole body vibration (WBV) on the electromyography (EMG) activity, cross-sectional area, and density of lower extremity muscles in individuals with chronic motor complete spinal cord injury (SCI).DesignCase series.MethodsSeven adult men with chronic (≥2 years), thoracic motor complete (AIS A–B) SCI completed a 40-week course of thrice-weekly intermittent PS-WBV therapy, in a flexed knee posture (160°), for 45 minutes per session at a frequency of 45 Hz and 0.6–0.7 mm displacement using the WAVE® Pro Plate, with an integrated EasyStand™ standing frame. EMG was measured in major lower extremity muscles to represent muscle activity during PS-WBV. The cross-sectional area and density of the calf muscles were measured using peripheral quantitative computed tomography at the widest calf cross-section (66% of the tibia length) at pre- and post-intervention. All measured variables were compared between the pre- and post-intervention measurements to assess change after the PS-WBV intervention.ResultsPS-WBV acutely induced EMG activity in lower extremity muscles of SCI subjects. No significant changes in lower extremity EMG activity, muscle cross-sectional area, or density were observed following the 40-week intervention.ConclusionsAlthough acute exposure to PS-WBV can induce electrophysiological activity of lower extremity muscles during PS in men with motor complete SCI, the PS-WBV intervention for 40 weeks was not sufficient to result in enhanced muscle activity, or to increase calf muscle cross-sectional area or density.

Effects of Physical Activity and Muscle Quality on Bone Development in Girls

Poor muscle quality and sedentary behavior are risk factors for metabolic dysfunction in children and adolescents. However, because longitudinal data are scarce, relatively little is known about how changes in muscle quality and physical activity influence bone development. In a 2-yr longitudinal study, we examined the effects of physical activity and changes in muscle quality on bone parameters in young girls. The sample included 248 healthy girls age 9-12 yr at baseline. Peripheral quantitative computed tomography was used to measure calf and thigh muscle density, an indicator of skeletal muscle fat content or muscle quality, as well as bone parameters at diaphyseal and metaphyseal sites of the femur and tibia. Physical activity was assessed using a validated questionnaire specific for youth. After controlling for covariates in multiple regression models, increased calf muscle density was independently associated with greater gains in cortical (β = 0.13, P < 0.01) and trabecular (β = 0.25, P < 0.001) volumetric bone mineral density and the bone strength index (β = 0.25, P < 0.001) of the tibia. Importantly, these relationships were generalized, as similar changes were present at the femur. Associations between physical activity and changes in bone parameters were weaker than those observed for muscle density. Nevertheless, physical activity was significantly (all P < 0.05) associated with greater gains in trabecular volumetric bone mineral density and the bone strength index of the distal femur. These findings suggest that poor muscle quality may put girls at risk for suboptimal bone development. Physical activity is associated with more optimal gains in weight-bearing bone density and strength in girls, but to a lesser extent than changes in muscle quality.

Changes in body composition in triathletes during an Ironman race

Triathletes lose body mass during an Ironman triathlon. However, the associated body composition changes remain enigmatic. Thus, the purpose of this study was to investigate Ironman-induced changes in segmental body composition, using for the first time dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Before and after an Ironman triathlon, segmental body composition and lower leg tissue mass, areas and densities were assessed using DXA and pQCT, respectively, in eight non-professional male triathletes. In addition, blood and urine samples were collected for the determination of hydration status. Body mass decreased by 1.9 ± 0.8 kg. This loss was due to 0.4 ± 0.3 and 1.4 ± 0.8 kg decrease in fat and lean mass, respectively (P < 0.01). Calf muscle density was reduced by 1.93 ± 1.04 % (P < 0.01). Hemoglobin, hematocrit, and plasma [K(+)] remained unchanged, while plasma [Na(+)] (P < 0.05), urine specific gravity and plasma and urine osmolality increased (P < 0.01). The loss in lean mass was explained by a decrease in muscle density, as an indicator of glycogen loss, and increases in several indicators for dehydration. The measurement of body composition with DXA and pQCT before and after an Ironman triathlon provided exact values for the loss in fat and lean mass. Consequently, these results yielded more detailed insights into tissue catabolism during ultra-endurance exercise.

Association of fat distribution with changes in bone outcomes in young girls

BackgroundChildhood obesity may impair bone growth but the relationship remains unclear.ObjectiveExamine longitudinal associations between total body fat (TBF), android fat (AF), and skeletal muscle fat (SMF) content, with bone outcomes in 260 girls aged 8–13y.MethodsPeripheral quantitative computed tomography measured changes in bone strength index (BSI, mg2/mm4), strength‐strain index (SSI, mm3) and volumetric bone density (vBMD, mg/cm3) at distal metaphyseal and diaphyseal regions of the femur (fem) and tibia (tib), and baseline calf (CMD) and thigh (TMD) muscle density (mg/cm3), an index of SMF content. Baseline TBF and AF were assessed by dual‐energy X‐ray absorptiometry.ResultsTBF and AF were positively associated with fem BSI (r=0.193; r=0.174), tib SSI (r=0.184; r=0.142), and fem trabecular vBMD (r=0.196; r=0.203), and inversely associated with tib cortical vBMD (r= −0.146; r= −0.172). Lower CMD and TMD was associated with fem BSI (r= −0.222; r= −0.145), tib BSI (r= −0.193; r= −0.128), fem tot vBMD (r= −0.208; r= −0.168), and trabecular vBMD (fem: r= −0.263; r= −0.192, tib: r= −0.215; r= − 0.161). CMD was significantly associated with tib SSI (r= −0.141) and tot vBMD (r= −0.130). ANCOVA showed that girls in the middle thirds of TBF and AF had higher fem and tib cortical vBMD than girls with greater TBF and AF. Greater changes in fem BSI, tot fem vBMD and fem and tib trabecular vBMD were observed in the lowest vs. highest thirds of CMD and TMD. All results were significant at p&lt;0.05.ConclusionsGains in TBF or AF may negatively impact tib bone development, while increases in CMD or TMD predict greater gains in various bone outcomes.Grant Funding Source: NIH/NICHD #HD‐050775

The Muscle-Bone Relationship in X-Linked Hypophosphatemic Rickets

We recently found that patients with X-linked hypophosphatemic rickets (XLH) have a muscle function deficit in the lower extremities. As muscle force and bone mass are usually closely related, we hypothesized that patients with XLH could also have a bone mass deficit in the lower extremities. The study objective was to assess the muscle-bone relationship in the lower extremities of patients with XLH. The study was carried out in the outpatients department of a pediatric orthopedic hospital. Thirty individuals with XLH (6 to 60 y; 9 male patients) and 30 age- and gender-matched controls participated. Calf muscle size and density as well as tibia bone mass and geometry were assessed by peripheral quantitative computed tomography. Muscle function was evaluated as peak force in the multiple 2-legged hopping test. Muscle force was significantly lower in XLH patients than in controls but muscle cross-sectional area did not differ (after adjustment for tibia length). External bone size, expressed as total bone cross-sectional area, was higher in the XLH group than in controls. The XLH cohort also had statistically significantly higher bone mineral content. Patients with XLH have increased bone mass and size at the distal tibia despite muscle function deficits.

Water- versus land-based exercise in elderly subjects: effects on physical performance and body composition

The aim of this study was to assess the effectiveness of a 24-week exercise protocol carried out in geothermal spring water to improve overall physical function and muscle mass in a group of healthy elderly subjects. A further aim was to compare this water-based protocol with a land-based protocol and a control group. For this purpose, 59 subjects were recruited and randomly allocated to three groups: aquatic group (AG), land group (LG), and control group (CG). AG and LG followed a 6-month, twice-weekly, multimodality exercise intervention. AG underwent the protocol in hot-spring water (36°C) while LG did it in a land-based environment. After the intervention, knee-extension strength was maintained in AG and LG. The 8-foot up-and-go test showed a reduction in both exercise groups (AG −19.3%, P < 0.05; LG −12.6%, P < 0.05), with a significantly greater decrease in AG. The back-scratch test revealed an improvement only in AG (25.8%; P < 0.05), while the sit-and-reach test improved in all groups. Finally, AG reduced fat mass by 4% (P < 0.05), and dominant forearm fat decreased by 9.2% (P < 0.05). In addition, calf muscle density increased by 1.8% (P < 0.05). In summary, both water- and land-based activities were beneficial in maintaining strength and in improving lower-body flexibility. Aquatic exercise appeared a better activity to improve dynamic balance. Thermal swimming pools and the use of rating of perceived exertion as a method of exercise monitoring should be considered potentially useful tools to enhance physical performance and body composition in healthy elderly.

Vitamin D status and functional performance in peripheral artery disease

The clinical implications of low vitamin D in peripheral artery disease (PAD) are unknown. We hypothesized that among individuals with PAD, lower levels of 25-hydroxyvitamin D would be associated with poorer functional performance, more adverse calf muscle characteristics, and poorer peripheral nerve function. Participants were 402 men and women with PAD who underwent measurement of 25-hydroxyvitamin D (DiaSorin radioimmunoassay) along with 6-minute walk testing, measurement of walking velocity at usual and fastest pace, computed tomography-measured calf muscle density, and peripheral nerve conduction velocity (NCV). Among PAD participants, 20.4% had 25-hydroxyvitamin D levels < 30 nmol/L, consistent with deficient vitamin D status. Adjusting for age, sex, and race, lower 25-hydroxyvitamin D levels were associated with poorer 6-minute walk performance (p trend = 0.002), slower usual-paced 4-meter walking velocity (p trend = 0.031), slower fast-paced 4-meter walking velocity (p trend = 0.043), and lower calf muscle density (p trend = 0.031). After additional adjustment for body mass index (BMI) and diabetes, none of these associations remained statistically significant. However, lower levels of 25-hydroxyvitamin D were associated with poorer peroneal NCV (p trend = 0.013) and poorer sural NCV (p trend = 0.039), even after adjusting for age, sex, race, BMI, comorbidities, smoking, physical activity, and other confounders. In conclusion, vitamin D deficiency is common among people with PAD encountered in clinical settings. After adjusting for BMI and diabetes mellitus, we found no significant associations of lower levels of 25-hydroxyvitamin D with poorer functional performance or calf muscle characteristics. Associations of low vitamin D levels with poorer peripheral nerve function require further study.

Role of Muscle Mass and Muscle Quality in the Association Between Diabetes and Gait Speed

OBJECTIVEOlder people with type 2 diabetes are at high risk of mobility disability. We investigated the association of diabetes with lower-limb muscle mass and muscle quality to verify whether diabetes-related muscle impairments mediate the association between diabetes and low walking speed.RESEARCH DESIGN AND METHODSWe performed a cross-sectional analysis of 835 participants (65 years old and older) enrolled in the InCHIANTI (Invecchiare in Chianti, aging in the Chianti area) population-based study. Total, muscular, and fat cross-sectional areas of the calf and relative muscle density were measured using peripheral quantitative computerized tomography. Indicators of muscle performance included knee-extension torque, ankle plantar flexion and dorsiflexion strength, lower-extremity muscle power, and ankle muscle quality (ratio of ankle strength to the muscle area [kilograms per centimeters squared]). Gait performance was assessed by 4- and 400-m walking speed. Diabetes was ascertained by standard American Diabetes Association criteria.RESULTSPrevalence of diabetes was 11.4%. After adjustment for age and sex, participants with diabetes had lower muscle density, knee and ankle strength, and muscle power and worse muscle quality (all P < 0.05). Diabetic participants were also slower on both 4-m (β: −0.115 ± 0.024 m/s, P < 0.001) and 400-m (β:−0.053 ± 0.023 m/s, P < 0.05) walking tests. In multivariable linear regression models, lower-limb muscle characteristics accounted for 24.3 and 15.1% of walking speed difference comparing diabetic and nondiabetic subjects in the 4- and 400-m walks, respectively.CONCLUSIONSIn older persons, diabetes is associated with reduced muscle strength and worse muscle quality. These impairments are important contributors of walking limitations related to diabetes.

Lower Physical Activity Is Associated with Skeletal Muscle Fat Content in Girls

Fat contained within skeletal muscle is strongly associated with obesity, type 2 diabetes mellitus, and metabolic syndrome. Physical inactivity may be a risk factor for greater fat infiltration within skeletal muscle during growth. We sought to examine the relationship between physical activity and skeletal muscle fat content of the calf and thigh in girls. Data from 464 girls, age 8-13 yr, were used to examine the relationship between physical activity and skeletal muscle fat content of the calf and thigh. Calf and thigh muscle density (mg·cm(-3)), an index of skeletal muscle fat content, was assessed at the 66% tibia and 20% femur sites relative to the respective distal growth plates of the nondominant limb using peripheral quantitative computed tomography. Physical activity level was classified by past-year physical activity questionnaire score. Muscle densities of the calf and thigh were inversely correlated with percent total body fat (r = -0.37 and -0.48, P values < 0.001) and total body fat mass (r = -0.33 and -0.40, P values < 0.001). Multiple linear regression with physical activity, ethnicity, maturity offset, and muscle cross-sectional area as independent variables showed that physical activity was independently associated with muscle densities of the calf (β = 0.14, P = 0.002) and thigh (β = 0.15, P < 0.001). Thus, lower physical activity was associated with higher skeletal muscle fat content. Our results suggest that a lower level of physical activity may lead to excess skeletal muscle fat content of the calf and thigh in girls.